This invention relates to a casting nozzle and a continuous steel casting mold surrounding the nozzle. The mold has a rectangular casting cross section and includes pairwise oppositely located endless casting belts and articulated endless dams arranged laterally along the casting belts. In particular, the invention is concerned with a seal between the casting nozzle and the continuous steel casting mold.
Continuous casting molds of the above-outlined type to which the molten metal is admitted in an open trough permit the continuous casting of lead, zinc and copper with high casting speeds. The air intake which necessarily occurs because of the use of the open trough does not adversely affect the casting operation and the quality of the cast products.
In contradistinction, in the steel casting there are used preferably vertically oriented oscillating molds whose molten metal level is covered by casting powder to prevent the admission of air. The steel melt is admitted from a distributor vessel into a vertically oriented submersion pipe which has outlet openings below the level of the melt. Because of the use of an oscillating mold, the casting speed of such a known process and that of the associated casting apparatus is limited to approximately 3 to 4 m/min.
Higher casting speeds of at least 10 m/min in steel casting may be materialized only with continuous casting molds which, like those mentioned earlier, have mold walls constituted by endless casting belts moved in the direction of casting and further have articulated lateral dams. Since the casting cross section is rectangular, a mutual sealing of the four cooperating mold walls is very difficult. Further, with regard to the quality of the cast product, care has to be taken by means of an appropriate design of the casting nozzle that no air is introduced into the continuous casting mold.
A satisfactorily functioning seal between the moving mold walls and the adjustable, but operationally stationary casting nozzle for separating the steel melt from air has not been developed heretofore. The provision of a satisfactory seal has also been made difficult by the fact that because of the liquid steel column in the distributor vessel, the seal has to be effective against a pressure of 0.5 bar. Further, after a certain period of service, the casting belts develop a wavy configuration which also has to be taken into account when designing the sealing elements. In addition, in any solution for a seal, the limited spatial conditions have to be considered which arise because of the relatively small cross-sectional area (normally in the order of magnitude of 80.times.170 mm) of the casting cross section.